Machine for the sharpening of impact rock drills with chisel cutting edges

ABSTRACT

A machine for sharpening of impact rock drills having a number of radially directed chisel cutting edges around the axis of the drill crown comprising a grinding wheel with a double-conically shaped peripheral surface and a holding chuck for the drill during the sharpening operation, said grinding wheel being mounted on a horizontal shaft and the chuck being guided in a bidirectional grinding movement.

United States Patent 1191 Lundberg June 19, 1973 MACHINE FOR THESHARPENING 0F 2,275,483 3 1942 Parker 51/219 R UX IMPACT ROCK DRILLSWITH CHISEL 2,424,470 7/1947 Kronwa1l..... 51/219 R X 2,847,800 8/1958Ingersoll 51/219 R X CUTTING EDGES 3,490,884 1/1970 Brierley 51/219 R xInventor: Biirje Oskar Lundberg, Tyreso,

Sweden Assignee: AB Grindex, Handen, Sweden Filedr June 25, 1971 Appl.No.: 157,041

[30] Foreign Application Priority Data June 26, 1970 Sweden 8904/70 [52]US. Cl. 51/92 R, 51/219 [51] Int. Cl B24b 3/33 [58] Field of Search51/92 R, 93, 219 R,

[56] References Cited UNITED STATES PATENTS 1,750,956 3/1930 Flanders51/92 R Primary ExaminerDonald G. Kelly Azromey-David H. Semmes wheelwith a double-comically shaped peripheral surface and a holding chuckfor the drill during the sharpening operation, said grinding wheel beingmounted on a horizontal shaft and the chuck being guided in abidirectional grinding movement.

4 Claims, 2 Drawing Figures PATENIEU 9 3. 739.529

L INVENTOR BORJE OSKAR LUNDBERG g g MAM/M l5 ATTORNEY MACHINE FOR THESHARPENING OF IMPACT ROCK DRILLS WITH CHISEL CUTTING EDGES The presentinvention relates to a machine for the sharpening of impact rock drillswith a plurality of radially directed chisel cutting edges distributedaround the axis of the drill crown, comprising a motor-driven grindingwheel formed by two frusto-conical surfaces meeting at a plane, and achuck positioned with its axis in said plane through the grinding wheelfor securely holding the drill crown or the drill shank, during thesharpening of the drill.

The object of the present invention is to provide such a sharpeningmachine by means of which impact rock drills of the kind defined abovecan be sharpened accurately, independent of the diameter of the grindingwheel which is variable according to wear.

According to the present invention, a machine for sharpening of impactrock drills having a number of radially directed chisel cutting edgesdistributed around the axis of a drill crown, comprises a motor-drivengrinding wheel with a peripheral surface defined by two intersectingfrusto-conical sections and a chuck having an axis located in the planeof the maximum perimeter of the grinding wheel for securely holding thedrill crown and a drill shank during the sharpening, said grinding wheelbeing mounted on a shaft, which rotates but is otherwise fixed duringthe sharpening, and said chuck being guided on one hand for areciprocating grinding movement in a first direction parallel with anintersection line in said plane of the grinding wheel between planesthrough adjacent cutting flanks of the tool, and on the other hand for afeeding movement in a second direction perpendicular to said directionand also lying in said plane of the grinding wheel.

The present invention will now be described more closely with referenceto the accompanying drawings, which illustrate one embodiment of asharpening assembly according to the present invention.

FIG. 1 shows the assembly in a side view and partly in a vertical crosssection, while FIG. 2 is a view perpendicular thereto, seen in thedirection of the arrows Il-ll in FIG. I.

In the embodiment illustrated on the drawings the grinding wheel issupported free-hanging on the horizontal shaft of a pneumatic motor 12.The latter is mounted on a support 14, which is built on a base plate15.

Laterally of the sharpening assembly 10, 12 a support 16 is built on thebase plate 15 having an upper support surface inclined downwardlytowards the base of support 14. The support 16 carries two fixed guiderods 18 in sleeve-shaped members 17, said guide rods being located atopposite sides of an imaginary vertical plane through the maximumperimeter of the grinding wheel 10. The guide rods are parallel to saidplane and with each other. On the fixed guide rods 18 two guide sleeves19 are positioned between the fixture members 17, said guide sleeves 19being substantially shorter than the distance between the fixturesleeves. The two guide sleeves are connected with each other to form aunit by means of a cross beam, not shown. Over the guide sleeves l9fixed dust protection sleeves 20 are threaded, and in which reduced endsof the guide sleeves 19 are received in a piston-like manner.

On each of the guide sleeves 19 a guide rod 22 is securely mounted in alaterally extending fixture sleeve 21, the axis of said guide rod 22being arranged at a right angle with the axis of the corresponding fixedguide rod 18 and being located in a plane, which is perpendicular to thebase plate 15. On each of guide rods 22 one of two axially movable guidesleeves 23 is provided, whch are rigidly connected with each other bymeans of a cross beam, not shown. Said cross beam carries a chuck 24 ina vertical plane through the grind ing wheel, the chuck beingpneumatically operated, for clamping the drill shank 25 in a horizontalposition in the imaginary vertical plane containing the maximumperimeter of the grinding wheel. In the case of a machine for thesharpening of drills with three cutting edges the jaws of the chuck 24are conveniently formed so that they hold the hexagonal drill steel indefined rotational positions, whereby a correct orientation of thecutting edges during the sharpening is secured. Dust protection sleeves26 are fixedly supported by the fixture sleeves 21, and the lower endsof guide sleeves 23 fit telescopically at their lower ends into sleeves26.

For the displacement of the drill chuck 24 and hence of the drill shank25 reciprocally in a direction parallel to the axes guide rods 22, apneumatic cylinder 27 is provided, and for the displacement of the chuckin a direction towards and away from the grinding wheel 10 in adirection parallel to the axes of the fixed guide rods 18, a feed screwwith a hand wheel 28 is provided. The

' amount of feed can be read on a rotable scale ring 29,

which is lockable in a desirable z-ero position relative a scale line onthe hand wheel 28.

On modern impact rock drills with hard metal cutting edges, for whichthe grinding wheel of the present in vention is primarily intended, thecutting edges have flat flank surfaces, which are joined in a commonedge. The planes through mutually adjacent flank surfaces associatedwith two mutually adjacent cutting edges intersect each other along astraight line, which forms an acute angle a with the axis of the drillhead or the drill shank. The reciprocal movement relative the grindingwheel must evidently be performed in a straight line, which is parallelwith the intersection line between the planes through the cuttingflanks, which intersect each other. This means that the guide rods 22must form the angle -a with the axis of the drill head or the drillshank. In the sharpening machine shown on the drawings the chuck 24 isadapted to hold the drill shank in a position parallel with the baseplate of the frame, and hence guide rods 18 must be inclined by theangle a to the base plate.

The angle B between the straight generatrices of the conical peripheralsurfaces of the grinding wheel intersecting each other must be equal tothe angle between two mutually adjacent flat cutting flanks belonging toadjacent cutting edges. On drills with four cutting edges the angle Bamounts to approximately 132 and on drills with three cutting edges toapproximately 147.

The grinding wheel 10 abuts linearily towards the two cutting flanksalong a straight line located in a radial plane. The linear abutmentbetween the grinding wheel and the cutting edge flanks of the drillcauses the torque on the grinding wheel to be at a minimum, whereby thegrinding wheelmotor 12 can be made small and light.

The grinding wheel 10 is enclosed in a protective hood 30, which at itslower portion is formed to a trough, from which grinding powder andcooling liquid is removed through the pipe 31. The grinding wheel iscaused to rotate in the direction of the arrow 32, which means that thewheel in the grinding zone has a movement directed from the hard metalcutting edges of the tool towards its body or shank, which is made ofsteel Thus the movement of the grinding wheel in this zone has acomponent which is directed inwardly away from the cutting edge of thetool.

I claim:

1. A machine for sharpening of impact rock drills having a number ofradially directed chisel cutting edges distributed around the axis of adrill crown, comprising:

A. a motor-driven grinding wheel having a peripheral surface defined bytwo intersecting frusto-conical sections;

B. a chuck having an axis located in the plane of the maximum perimeterof the grinding wheel for securely holding the drill crown and a drillshank during the sharpening;

C. a shaft mounting said grinding wheel with said shaft being rotatablebut otherwise fixed during the sharpening;

D. means for guiding said chuck on one hand for a reciprocating grindingmovement in a first direction parallel with an intersection line in saidplane of the grinding wheel between planes through adjacent cuttingflanks of the tool, and on the other hand for a feeding movement in asecond direction perpendicular to said direction and also lying in saidplane of the grinding wheel;

B. said guide means for said chuck including:

i. a base plate;

ii. a guide for the feeding movement of the chuck in said firstdirection being inclined at an acute angle towards said base plate, suchthat the axis of the chuck and hence the axis of a drill shank securedin the chuck are parallel with the base plate.

2. A machine for sharpening of impact rock drills having a number ofradially directed chisel cutting edges distributed around the axis of adrill crown, comprising:

A. a motor-driven grinding wheel having a peripheral surface defined bytwo intersecting frusto-conical sections;

B. a chuck having an axis located in the plane of the maximum perimeterof the grinding wheel for securely holding the drill crown and a drillshank during the sharpening;

C. a shaft mounting said grinding wheel with said shaft being rotatablebut otherwise fixed during the sharpening;

D. means for guiding said chuck on one hand for a reciprocating grindingmovement in a first direction parallel with an intersection line in saidplane of the grinding wheel between planes through adjacent cuttingflanks of the tool, and on the other hand for a feeding movement in asecond direction perpendicular to said direction and also lying in saidplane of the grinding wheel;

E. said guide means for said chuck including:

i. a base plate;

ii. two parallel fixed guide rods inclined towards said base plate;

iii. two guide sleeves slidable respectively on said two fixed guiderods;

iv. two movable guide rods respectively carried by said two guidesleeves and perpendicular to the plane through said fixed guide rods;and

v. two further guide sleeves slidable along said movable guide rods andjoined together as a unit and supporting said chuck.

3. A sharpening machine as claimed in claim 1, including a rotatablymounted feed screw having a hand wheel for causing feeding movement insaid first direction, and a scale ring rotatably supported andadjustable to a desirable angular position, and a scale line on saidhand wheel cooperating with said scale ring.

4. A sharpening machine as claimed in claim 1 for the sharpening ofdrills with three cutting edges, said chuck having jaws shaped forfixedly securing a hexagonal drill steel in correct grinding position.

1. A machine for sharpening of impact rock drills having a number ofradially directed chisel cutting edges distributed around the axis of adrill crown, comprising: A. a motor-driven grinding wheel having aperipheral surface defined by two intersecting frusto-conical sections;B. a chuck having an axis located in the plane of the maximum perimeterof the grinding wheel for securely holding the drill crown and a drillshank during the sharpening; C. a shaft mounting said grinding wheelwith said shaft being rotatable but otherwise fixed during thesharpening; D. means for guiding said chuck on one hand for areciprocating grinding movement in a first direction parallel with anintersection line in said plane of the grinding wheel between planesthrough adjacent cutting flanks of the tool, and on the other hand for afeeding movement in a second direction perpendicular to said directionand also lying in said plane of the grinding wheel; E. said guide meansfor said chuck including: i. a base plate; ii. a guide for the feedingmovement of the chuck in said first direction being inclined at an acuteangle towards said base plate, such that the axis of the chuck and hencethe axis of a drill shank secured in the chuck are parallel with thebase plate.
 2. A machine for sharpening of impact rock drills having anumber of radially directed chisel cutting edges distributed around theaxis of a drill crown, comprising: A. a motor-driven grinding wheelhaving a peripheral surface defined by two intersecting frusto-conicalsections; B. a chuck having an axis located in the plane of the maximumperimeter of the grinding wheel for securely holding the drill crown anda drill shank during the sharpening; C. a shaft mounting said grindingwheel with said shaft being rotatable but otherwise fixed during thesharpening; D. means for guiding said chuck on one hand for areciprocating grinding movement in a first direction parallel with anintersection line in said plane of the grinding wheel between planesthrough adjacent cutting flanks of the tool, and on the other hand for afeeding movement in a second direction perpendicular to said directionand also lying in said plane of the grinding wheel; E. said guide meansfor said chuck including: i. a base plate; ii. two parallel fixed guiderods inclined towards said base plate; iii. two guide sleeves slidablerespectively on said two fixed guide rods; iv. two movable guide rodsrespectively carried by said two guide sleeves and perpendicular to theplane through said fixed guide rods; and v. two further guide sleevesslidable along said movable guide rods and joined together as a unit andsupporting said chuck.
 3. A sharpening machine as claimed in claim 1,including a rotatably mounted feed screw having a hand wheel for causingfeeding movement in said first direction, and a scale ring rotatablysupported and adjustable to a desirable angular position, and a scaleline on said hand wheel cooperating with said scale ring.
 4. Asharpening machine as claimed in claim 1 for the sharpening of drillswith three cutting edges, said chuck having jaws shaped for fixedlysecuring a hexagonal drill steel in correct grinding position.